Conventionally, there has been known a power-supplying device that supplies power to a power-supplied device in a non-contact manner by using electromagnetic induction. Such a power-supplying device uses a mechanism to generate an electromotive force on the secondary coil side of a power-supplied device by feeding a current to the primary coil side. By using this electromagnetic induction to supply power, the displacement between the primary coil and the secondary coil will become the less power efficiency or cause excessive power supply. For this reason, Japanese Patent Laid-Open No. 9-103037 discloses a method to control the power to be supplied, based on the information received from a power-supplied device.
The above conventional technique, however, is not based on the assumption that power is simultaneously supplied to a plurality of power-supplied devices in a non-contact manner by using one primary coil. Assume a situation in which power is simultaneously supplied to a plurality of power-supplied devices in a non-contact manner by using one primary coil. In this case, in order to properly supply power to the respective power-supplied devices, it is necessary to control power to be supplied in accordance with the power-supplied devices with different allowable amounts associated with power supply, for example, allowable voltage and current values.